The spatiotemporal effect of sea surface temperature on the seasonal migrations of the bonnethead, Sphyrna tiburo

Abstract To better understand the effects of climatic variation on migratory behavior, we used passive acoustic telemetry to track the migrations of 44 bonnetheads, Sphyrna tiburo , tagged in the North Edisto River, South Carolina . We monitored individuals for up to 2804 days along ~ 1070 km of United States Atlantic coastline. The majority of these sharks exhibited strong site fidelity and returned annually, residing in the estuary from April to November. Climatic migrations occurred annually and overwintering habitats were located in nearshore Atlantic waters from Georgia to central Florida. Given the strong site fidelity, we were able to measure the distance and timing of migration and assess, for the first time to our knowledge, the interannual effects of climatic variation on the return migrations of individual sharks. We found that shark size and winter sea surface temperature had significant effects on the migration distance of female S. tiburo , the latter also contributing to interannual variation in migration duration and the date of arrival to overwintering areas. These data suggest that overwintering habitats are selected, at least in part, based on thermal preference or tolerance and not solely physical location. These results indicate that climate change may affect both the timing and distance of migrations for migratory sharks and highlight the benefit of maintaining long-term longitudinal datasets for studying complex animal behavior.